Search Results (171)

A multi-objective genetic algorithm is tailored to optimize the design of a wavelength interleaver/deinterleaver device. An interleaver combines data streams from two physical channels into one. The deinterleaver does the opposite job. The WDM requirements for this device include channel spacing of 50 GHz, channel bandwidth of 20 GHz, free spectral range of 100 GHz, maximum channel dispersion of 30 ps/nm, and maximum crosstalk of −23 dB. The challenges for the optimization process include the lack of a closed-form expression for the device performance and the trade-off between the conflicting performance parameters. So, for this multi-objective problem, the proposed approach maneuvers to find a compromise between the performance parameters within a few minutes, saving the designer the laborious design process previously proposed in the literature, which relies on visually inspecting the Z-plane for the dynamics of the transmission poles and zeros. Designs of better performance are achieved, with fewer ring resonators, a channel dispersion as low as 1.6 ps/nm, and crosstalk as low as −30 dB. Full article

The growing adoption of IoT applications has led to increased use of low-power microcontroller units (MCUs) for energy-efficient, local data processing. However, deploying deep neural networks (DNNs) on these constrained devices is challenging due to limitations in memory, computational power, and energy. Traditional methods like cloud-based inference and model compression often incur bandwidth, privacy, and accuracy trade-offs. This paper introduces a novel Decentralized Distributed Sequential Neural Network (DDSNN) designed for low-power MCUs in Tiny Machine Learning (TinyML) applications. Unlike the existing methods that rely on centralized cluster-based approaches, DDSNN partitions a pre-trained LeNet across multiple MCUs, enabling fully decentralized inference in wireless sensor networks (WSNs). We validate DDSNN in a real-world predictive maintenance scenario, where vibration data from an industrial pump is analyzed in real-time. The experimental results demonstrate that DDSNN achieves 99.01% accuracy, explicitly maintaining the accuracy of the non-distributed baseline model and reducing inference latency by approximately 50%, highlighting its significant enhancement over traditional, non-distributed approaches, demonstrating its practical feasibility under realistic operating conditions. Full article

This paper presents a wideband low-power/low-voltage 60-GHz low-noise amplifier (LNA) in a 28-nm bulk CMOS technology. The LNA has been designed for high-speed millimeter-wave (mm-wave) communications. It consists of two pseudo-differential amplifying stages and a buffer stage included for 50-Ohm on-wafer measurements. Two integrated input/output baluns guarantee both simultaneous 50-ohm input–noise/output matching at input/output radio frequency (RF) pads. A power-efficient design strategy is adopted to make the LNA suitable for low-power applications, while minimizing the noise figure (NF). Thanks to the adopted design strategy, the post-layout simulation results show an excellent trade-off between power gain and 3-dB bandwidth (BW_3dB) with 13.5 dB and 7 GHz centered at 60 GHz, respectively. The proposed LNA consumes only 11.6 mA from a 0.9-V supply voltage with an NF of 8.4 dB at 60 GHz, including the input transformer loss. The input 1 dB compression point (IP_1dB) of −15 dBm at 60 GHz confirms the first-rate linearity of the proposed amplifier. Human body model (HBM) electrostatic discharge (ESD) protection is guaranteed up to 2 kV at the RF input/output pads thanks to the input/output integrated transformers. Full article

The recent advancements in high-frequency, high-power switching devices require the development of non-invasive, cost-effective sensors for signal diagnostics. In this context, planar sensors have emerged as promising candidates for voltage and current sensing due to their compatibility with printed circuit boards (PCBs). However, previously proposed voltage planar sensors exhibit trade-offs between high bandwidths and responsivity, limiting their usage to sub-GHz applications. This study introduces a planar voltage sensor that leverages geometric optimization using software-assisted design to enhance bandwidth without compromising sensitivity. The optimized sensors demonstrate an extended bandwidth response up to 4 GHz and accurate recovery of fast transient signals validated through experimental measurements, which represents a significant step forward in broadband sensing for high-power applications. Full article

The rapid advancement of electronic technology demands circuit designs that minimize power consumption while maximizing performance. The power supply rejection ratio (PSRR) is a critical metric for quantifying an amplifier’s ability to suppress supply noise, yet accurately predicting PSRR in high-frequency domains and complex multi-stage architectures is increasingly challenging. In this work, we introduce a new framework for PSRR prediction that overcomes these limitations. Leveraging a simplified circuit abstraction based on Thevenin’s theorem, we reduced multi-stage operational amplifiers to “black-box” models—collapsing intricate small-signal networks into a tractable form without sacrificing accuracy. Building on this foundation, we proposed the Power-Supply Rejection Gain-Bandwidth (PGB) metric, which concisely captures the trade-off between an amplifier’s DC PSRR and the frequency range over which that rejection is effective. Using PGB, designers gain an intuitive figure-of-merit for early-stage optimization of PSRR. We validated the efficacy of the combined black-box modeling and PGB approach through detailed case studies, including a 180 nm CMOS two-stage op-amp design. These findings confirmed that the proposed black box plus PGB framework can reliably guide the design of analog circuits with stringent PSRR requirements. Full article

Aiming at the problem of the through-core current sensor based on cable partial discharge detection having difficulty in compatibility with high sensitivity and wide detection frequency band, this paper proposes a design method for an ultra-high-frequency through-core current sensor. Firstly, the sensor circuit model was established, and the relationship between the sensor hardware parameters, and the bandwidth and sensitivity was derived. Subsequently, a multi-objective particle swarm optimization model was established. The sensitivity and bandwidth were taken as the objective functions, and the hardware parameters were regarded as the decision variables. Constraint conditions were set according to the cable size, self-integration working mode, etc. The optimal hardware parameters were obtained through solution and calculation. Finally, an ultra-high-frequency through-core current sensor was fabricated, and the bandwidth and sensitivity of the sensor at different frequencies were tested. The test results of cable partial discharge signals demonstrate that the designed sensor maintains a sensitivity of no less than 20.46 V/A within the 3 MHz to 200 MHz frequency range. This performance not only satisfies the fundamental sensitivity requirement of 5 V/A in the 3–30 MHz band for cable partial discharge detection but also resolves the inherent trade-off between sensitivity and detection bandwidth, exhibiting superior performance compared to conventional sensors. Full article

Edge intelligence is an emerging paradigm generated by the deep integration of artificial intelligence (AI) and edge computing. It enables data to remain at the edge without being sent to remote cloud servers, lowering response time, saving bandwidth resources, and opening up new development opportunities for multi-user intelligent services (MISs). Although edge intelligence can address the problems of centralized MISs, its inherent characteristics also introduce new challenges, potentially leading to serious security issues. Malicious attackers may use inference attacks and other methods to access private information and upload toxic updates that disrupt the model and cause severe damage. This paper provides a comprehensive review of multi-user privacy protection mechanisms and compares the network architectures under centralized and edge intelligence paradigms, exploring the privacy and security issues introduced by edge intelligence. We then investigate the state-of-the-art defense mechanisms under the edge intelligence paradigm and provide a systematic classification. Through experiments, we compare the privacy protection and utility trade-offs of existing methods. Finally, we propose future research directions for privacy protection in MISs under the edge intelligence paradigm, aiming to promote the development of user privacy protection frameworks. Full article

For high-power magnetic resonance imaging (MRI) radio frequency (RF) combiners operating in the frequency range from 60 MHz to 300 MHz, the primary challenges lie in achieving high-power transmission capability while minimizing the insertion loss (IL), reducing the physical dimensions, and meeting application bandwidth requirements. This paper presents a high-performance RF power combiner based on capacitor-loaded microstrip technology for 3.0T MRI radio frequency power amplifier (RFPA) systems. The proposed combiner features low loss, high integration, and miniaturization, and it comprises multiple branches, each employing microstrip lines and capacitors in a series–parallel arrangement to achieve an impedance transformation of 50 Ω to 100 Ω. Each branch was designed through theoretical analysis and electromagnetic simulations to achieve a line length 30% shorter than λ/4, a 6.2 mm line width, and 0.08 dB IL at the 3.0T MRI operation frequency band. A two-way to one-way combiner was further designed using this branch structure to achieve 0.2 dB IL through simulation optimization. A four-way to one-way combiner was then constructed by cascading two-way combiners and optimized via ADS-HFSS software(ADS2014 HFSS19) co-simulation. The fabricated combiner module uses an FR4 substrate and achieves a 0.4 dB insertion loss, −25 dB return loss, and 25 dB port isolation at 128 MHz ± 1 MHz, with compact dimensions (320 × 200 × 10 mm). To ensure high power capability, thermal analysis was performed to confirm that the module’s power-handling capacity exceeded 8 kW, and experimental validation with the 8 kW 3.0T RFPA demonstrated a stable temperature rise of approximately 2 °C. In this study, the innovative single-branch topology and the RF high-power four-to-one combiner for 3.0T MRI systems were used, resolving the trade-offs between power-handling capability, insertion loss, structural compactness, and operating bandwidth in MRI power combiners. The combiner was successfully integrated into the 3.0T MRI RFPA system, reducing the overall dimensions of the RFPA system and simplifying its installation, thereby enabling high-quality imaging validation. This solution demonstrates the scalable potential of the design for other high-field MRI systems operating in the MHz range (from tens to hundreds of MHz), including in 1.5T and 7.0T MRI systems. Full article

This paper presents an RF switch chip with a wide operating bandwidth from 6 to 18 GHz, designed for RF front-end applications in mobile communications. A series-parallel topology combined with a stacked transistor structure was employed to improve power handling while maintaining low insertion loss and high isolation. To further optimize isolation and return loss, LC resonant circuits were introduced by utilizing off-state transistors as capacitive elements. Compared to existing designs, the proposed switch achieved an improved trade-off between bandwidth, power capacity, and port performance. Measurement results showed insertion loss below 1.917 dB, isolation above 38.839 dB, return loss better than 13.075 dB, and 1 dB input compression point above 32 dBm at 12 GHz, confirming the effectiveness and novelty of the broadband design. Full article

Optical 3 dB power splitters are fundamental building blocks for advanced silicon photonic integrated circuits, with applications ranging from high-speed modulators to optical phased arrays and programmable photonic processors. However, 3 dB power splitters are commonly hampered by trade-offs in device dimensions, operation bandwidth, and fabrication technology. In this paper, we present a compact and ultra-broadband 3 dB power splitter based on segmented adiabatic tapered rib waveguides, with a length of 23.4 μm. The simulated splitter achieved an output transmission efficiency exceeding 48% over a large wavelength of 400 nm (1200–1600 nm). The power splitter was successfully fabricated on a commercial platform and exhibited excellent splitting ratios within 50 ± 3.8% and insertion losses below 0.38 dB over the range of 1260–1360 nm and 1525–1600 nm. Additionally, a high-speed Mach–Zehnder modulator based on the power splitter was built, demonstrating 40 Gbps NRZ signal modulations across both O-band and C-band. The proposed splitter and modulator are promising elements for large-scale and broadband integrated photonic systems. Full article

With the rapid advancement of Internet of Things (IoT) technology, ultra-wideband flexible transparent antennas have garnered substantial attention for their potential applications in wireless communication devices. Poly(methyl methacrylate) (PMMA), renowned for its exceptional optical properties and favorable processing characteristics, has been extensively utilized as a transparent substrate material for antennas. However, the intrinsic brittleness of transparent PMMA substrates poses a significant limitation in applications such as flexible antennas. In this study, we introduce a superspreading strategy to address the complex trade-off among transparency, toughness, and dielectric properties in flexible electronics through molecular disorder engineering. The PMMA films fabricated via this superspreading strategy exhibit a visible transmittance of 85–95% at 400 nm, a toughness of 9 × 10⁵ J/m³ (representing an enhancement of 150–225% compared to conventional methods), and a frequency-stable permittivity (ε_r = 3.6 ± 0.05) within the 9–12 GHz range. These films also feature a precisely tunable thickness range of 5.5–60 μm. The PMMA-based flexible transparent antenna demonstrates a gain of 2–4 dBi and a relative bandwidth of 40%, thereby confirming its suitability for ultra-wideband applications. Collectively, this research presents a promising candidate for the development of ultra-wideband flexible transparent antennas. Full article

Impulse ultrawideband (UWB) synthetic aperture radar (SAR) combines high-azimuth-range resolution with robust penetration capabilities, making it ideal for applications such as through-wall detection and subsurface imaging. In such systems, the performance of UWB antennas is critical for transmitting high-power, large-bandwidth impulse signals. However, two primary factors degrade radar imaging quality: (1) inherent limitations in antenna radiation efficiency, which lead to low-frequency signal loss and subsequent time-domain ringing artifacts; (2) impedance mismatch at the antenna terminals, causing standing wave reflections that exacerbate the ringing phenomenon. This study systematically analyzes the mechanisms of ringing generation, including its physical origins and mathematical modeling in SAR systems. Building on this analysis, we propose a Bayesian ringing suppression algorithm based on sparse optimization. The method effectively enhances imaging quality while balancing the trade-off between ringing suppression and image fidelity. Validation through numerical simulations and experimental measurements demonstrates significant suppression of time-domain ringing and improved target clarity. The proposed approach holds critical importance for advancing impulse UWB SAR systems, particularly in scenarios requiring high-resolution imaging. Full article

The terahertz (THz) band, ranging from 0.1 to 10 THz, offers substantial bandwidths that are essential for meeting the ever-increasing demands for high data rates in future wireless communication systems. This paper presents a comprehensive comparative analysis of various multicarrier waveforms suitable for THz-band communications. We explore the performance, advantages, and limitations of several waveforms, including Orthogonal Frequency Division Multiplexing (OFDM), Filter Bank Multicarrier (FBMC), Universal Filtered Multicarrier (UFMC), and Generalized Frequency Division Multiplexing (GFDM). The analysis covers key parameters such as spectral efficiency, the peak-to-average power ratio (PAPR), robustness to phase noise, and computational complexity. The simulation results demonstrate that while OFDM offers simplicity and robustness to multipath fading, it suffers from high PAPR and phase noise sensitivity. FBMC and UFMC, with their enhanced spectral efficiency and reduced out-of-band emissions, show promise for THz-band applications but come at the cost of increased computational complexity. GFDM presents a flexible framework with a trade-off between complexity and performance, making it a potential candidate for diverse THz communication scenarios. Our study concludes that no single waveform universally outperforms the others across all metrics. Therefore, the choice of multicarrier waveform for THz communications should be tailored to the specific requirements of the application, balancing performance criteria and implementation feasibility. Future research directions include the development of hybrid waveforms and adaptive techniques to dynamically optimize performance in varying THz communication environments. Full article

A clustered distributed storage system (DSS), also called a rack-aware storage system, is a distributed storage system in which the nodes are grouped into several clusters. The communication between two clusters may be restricted by their connectivity; that is to say, the communication cost between nodes differs depending on their location. As such, when repairing a failed node, downloading data from nodes that are in the same cluster is much cheaper and more efficient than downloading data from nodes in another cluster. In this article, we consider a scenario in which the failed nodes only download data from nodes in the same cluster, which is an extreme and important case that leverages the fact that the intra-cluster bandwidth is much cheaper than the cross-cluster repair bandwidth. Also, we study the problem of repairing multiple failures in this article, which allows for collaboration within the same cluster, i.e., failed nodes in the same cluster can exchange data with each other. We derive the trade-off between the storage and repair bandwidth for the clustered DSSs and provide explicit code constructions achieving two extreme points in the trade-off, namely the minimum storage clustered collaborative repair (MSCCR) point and the minimum bandwidth clustered collaborative repair (MBCCR) point, respectively. Full article

This paper presents two novel avalanche photodiode (APD) array structures designed to significantly enhance both detection area and bandwidth, overcoming the common trade-off between these parameters in conventional photodetectors. The impact of various parameters on the bandwidths of the two distinct array structures was theoretically simulated. Experimental validation using the self-fabricated 2 × 2 array on PCB board confirmed the bandwidth enhancement realized through inductor integration, with one APD array demonstrating an increase to 780 MHz (1.41 times greater) and another showing an increase to 1.21 GHz (1.35 times greater). Unlike prior works where array bandwidth is often lower than single detectors, our structures maintain high bandwidth while expanding the detection area. Structure 2 is particularly recommended over Structure 1 because of its lower noise, better signal-to-noise ratio (SNR), and reduced power consumption. Full article